1. Field of the Invention
This invention relates to the field of automobiles, and more particularly to an automobile that is inexpensive to produce, has a high crash-worthiness, expends low emissions in operation, results in low waste production in its manufacture, and offers dramatic improvement in ease of use and maintenance.
2. Brief Description of the Prior Art
The automobiles market is enormous, there being approximately 540 million cars and trucks in the world, 123 million cars, 4.4 million motorcycles operating in the United States alone. Ten million cars are sold in the U.S. per year, 1 million subcompacts, 1 million motorcycles, and 400,000 all-terrain vehicles. Additionally, another 10 million used cars were sold last year. Of the 42 million U.S. households, 50% have two or more cars, and the owners do a considerable amount of commuting and running of errands. In the U.S., the average round trip daily commute is about 22 miles. For this type of vehicular travel, the public has often resorted to the use of economy subcompacts, motorcycles, and scooters as second vehicles to fulfill the need.
Approximately 108 million Americans drive to work, up more than one third from just a decade ago. Two thirds of all population growth has taken place in the suburbs requiring extra driving distances. Women make up almost half the workforce and drive 50% more than they did in 1983.
The automobile has come to its outer limits as we know it. Many of the major problems that are facing the world can be traced directly back to its manufacture and use, including the massive pollution of air, land, and water by the enormous industrial machines it requires to be manufactured, its own direct poisoning of the atmosphere from its use and disposal, and the millions of people that are killed and injured attributable to its use. On the one hand, the automobile is an essential link in modern civilization, but at the same time a major contribution to its growing problems. Then again, the modern automobile is essentially the same as it was when it was invented with only minor design differences.
There have been some improvements since the concept of the automobile, however. Ford mass-produced the automobile making it affordable to the masses. Mercedes created a well-engineered car, and the Japanese created an affordable well-engineered car with substantially zero defects and capable of rapid improvements. But today's automobile is still essentially the same machine.
Several factors have motivated the inventor to depart from the rather standard automobile structure and manufacture techniques, and the resultant design is the basis for the present invention.
One of these factors is safety. The U.S. fatality deaths per 100 million miles was 7.5 in 1950 and was 2.0 in 1989. The U.S. is second only to Sweden as the safest driving country. There is good reason to believe that this improved fatality rate can be even lower.
Another factor is the use of more plastics in automobiles. The average car's plastic content has more than doubled since 1972. Plastic bumper covers, interior panels, trim moldings, bumper beams, fuel tanks, valve covers, and oil pans are commonly used today.
Another factor is the size and weight of the automobiles. Big cars on the road made up 51% of the automobile fleet in 1977 and 39% in 1990. Curb weight of the average American car was 4500 pounds in 1972, and has dropped to 3200 pounds in 1990.
Yet another factor is cost. Cars have become very expensive. The average new car price tag is $12,500.00, and with interest on payments and insurance at about $1200.00 per year, there has been an increased demand for low cost automobiles. Cars scrapped as percent of those on the road was 9% in 1971, and in 1991, it was 6.5%. Average age of cars on the road in 1971 was 5.5 years, and in 1991 it was 8 years. All of the above statistical factors, except for cost, have been steadily improving over the years. However, there would appear to be a clear need for a major redesign of the modern automobile and its construction in order to realize a step-wise improvement in these factors, including lowering the price of automobiles. It is the object of the present invention to fulfill that need.
Some of the design concepts, materials, and assembly techniques to be discussed in this specification have, at least to some extent been explored in the prior art.
In the helicopter industry, the utilization of advanced composites at the production stage permits the construction of a high efficiency machine capable of performances unthinkable a few years ago. Conventional structures contain low cost materials which require increasingly expensive manufacturing procedures. On the other hand, composites are more expensive, but permit the adoption of automatic manufacturing procedures with a net economic gain of approximately 30-50%. The introduction of advanced composites has allowed the reliability and ease of maintenance of the machines to increase because the number of included components, and hence the probability of breakdown and malfunction risk, have been drastically reduced. The payload at equal power is increased as a direct consequence of the lighter structure. Finally, the overall utilization cost of the helicopter has decreased, because of the decrease in the original purchase price and lower operating cost.
In recent years, composite materials have been very successfully applied to racing car chassis by employing methods which replace more traditional production methods utilizing riveted steel sheets. The advantages from an engineering point of view can be quantified in terms of increased mass specific torsional and bending stiffness, improvements in crash-worthiness, ease of repair and reuse, and structural stability over time. Also, a stable mold gives reproducible dimensional accuracy on chassis production runs. Tooling cost comparisons show molding equipment to be significantly less than steel presses.
Structural ceramics and ceramic composites, known in the industry as "engineered ceramics" as well as "Advanced Engineering Ceramics" (AEC), are being used in a wide variety of automotive applications requiring high strength. Silicon carbide fibers have been added to increase strength of silicon nitride and alumina automotive components such as piston heads, bearings, turbo rotors, engine valves, engine blocks and valve seats.
Engineered ceramic materials have many uses. However, engineered ceramics have heretofore not been used in the manufacture of automobile chassis, although similar materials already exist in nature, dental enamel, bones, and sea shells, being examples. Engineered ceramics can be formed at room temperature. That is, it can be "cold molded".
One of the many virtues of ceramics is their ability to withstand service temperatures up to 1,650.degree. C.
Ceramics tend to be weak in tension, but strong in compression. In metals, compression strength is near the tensile strength, but compressive strength may be ten times the tensile strength in a ceramic. The discrepancy between tensile and compressive strengths is in part due to the brittle natures of ceramics. In tension, ceramics, unlike metals, are unable to yield and relieve the stress. This weakness is solved by the design of the chassis of the present invention, utilizing a compound curve egg-shaped mold which is one of the strongest shapes known. The use of engineered ceramics also addresses this problem. Single-ceramics usually are stronger than those with more than one phase. Machining can introduce flaws in a part. Sintering to final shape as is done in the present invention not only saves time and labor, it produces a stronger part.
Glass fiber materials are very strong in tension, with tensile strengths up to 4,300 MPa (624.times.10.sup.3) psi compared to only 400 MPa (58.times.10.sup.3) psi for ordinary steel. Glass fiber can reinforce ceramic-matrix composites.
There are many engineering ceramics applicable for use in producing the present invention: hot pressed and sintered carbides such as beryllium carbide, titanium carbide, columbian carbide, tantalum carbide and zirconium carbide; silicon carbides such as silicon bonded, silicon nitride bonded, KT SIC, boron carbide; and reaction bonded and hot pressed silicon nitrides. High-alumina ceramics and carbides with metal binders are also applicable.
Dow Chemical produces silicon ceramic molds along with fifty others situated in the US, Japan, Canada and Europe. They produce primarily for the automotive, aerospace, computer and high tech industries.
The race car industry has made use of a body design known as monocoque, i.e. a type of construction in which the outer skin carries all or a major part of the stresses. It is a type of vehicle construction in which the body is integral with the chassis. A number of different materials have been proposed for monocoque chassis. Gel casting is a process in which a slurry of ceramic powder (silicon nitride) in a solution of organic monomers is cast in a mold. The mixture is polymerized in situ to form jelled parts in complex shapes which overcome some of the major drawbacks of injection molding. Other applicable formulas are: organo metallic derived ceramics, silicon carbide ceramics, carbon fiber reinforced plastics, thermoplastic resin composition made of glass balloons, and reinforcing fiber in thermoplastic resin. Also, silicon nitride whose properties include excellent high temperature strength, wear resistance, and light weight have been used in the production of components such as turbo charger rotors, rocker arm tips, and ball bearings, all commercially produced to exhibit high strength and reliability. Another formula is phenolic resins which have been employed in the body and turbine components of water pumps, carburetors, injection pumps, and some parts of the automatic transmission of an automobile. Its ability to achieve high loading have allowed the possibility to replace aluminum components in automobiles. Organic polymers of thermosetting and thermoplastics applications have been used in spacecraft nose cones, internal protective covers for rocket engine exhaust systems, and construction for combustion engines.
Several publications relating to engineered ceramic materials are available as reference materials. All of the following documents are of interest in this field and all are incorporated herein by reference for purposes of indicating the background of the invention and illustrating the state of the art relative to the use of engineered ceramic materials:
"Gelcasting of Alumina" by Albert C. Young, Ogbemi O. Omatete, Mark A. Janney, and Paul A. Menchhofer, Journal of the American Ceramic Society, Vol. 74, No. 3, March 1991, Pages 612-618; PA1 "Gelcasting--A New Ceramic Forming Process" by Ogbemi O. Omatete, Mark A. Janney, and Richard A. Strehlow, American Ceramic Society Bulletin, Vol. 70, No. 10, 1991; PA1 "Guide to Engineered Materials", Advanced Materials & Processes/incorporating Metal Progress, Pages 30-49. PA1 Catalog of WESGO Technical Ceramics and Brazing Alloys, 477 Harbor Boulevard, Belmont, Calif. 94002; and PA1 Catalog of CERCOM Inc., 1960 Watson Way, Vista, Calif. 92083.
Adhesives have been used to bond aircraft components made of plastics, high temperature metal, or polymer matrix composites, including acrylic, bismalaimide, cyanoacrylate, epoxy, phenolic, polyimides, silicone, and urethane. A beneficial side effect of this type of bonding has been to baffle or suppress engine noise.